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3 Abstract Lipid rafts are defined as islets in the membranes of eucaryotic cells with different composition from the rest of the membrane. They appear spontaneously due to phase separation of different membrane components and are proposed to serve as platforms for concentration of selected signaling proteins. However, evidence for their existence is still indirect, despite more than decade of intense research. Some new approaches show that the fluctuations of membrane composition are more diverse and are caused more likely by presence of proteins than by lipid phase separation. We performed bioinformatical search looking for new signaling proteins targeted to putative rafts. We have identified several proteins and out of them phosphodiesterase 8a (PDE 8a) was salected for further research. To prepare the mouse monoclonal antibody we expressed and purified fragment of PDE 8a fused with GST. After immunisation we obtained one clone producing antibodies tentatively positive on western blot and by indirect immunofluorescence. We predicted that PDE 8a is targeted to putative rafts by N-terminal myristoylation and palmitoylation. To clarify, whether these modifications are present in the strusture of PDE 8a we prepared mutants of the PDE 8a N-terminal region lacking myristoylation, palmitoylation or both. These... |
